1. Field of the Invention
This invention relates to an ophthalmologic measuring apparatus, and in particular to a cornea shape measuring apparatus.
2. Description of the Prior Art
A keratometer for measuring cornea shape is usually used to measure the three elements of a cornea, i.e., the curvature, the degree of astigmatism and the direction of astigmatic axis, and in addition, is used to inspect the base curve of contact lenses.
In the conventional keratometer, the shape of the corneal reflection image of a ring-shaped chart has been observed and measured by naked eyes and therefore, the magnification has been set to a high level to obtain satisfactory accuracy, thereby enlarging the corneal reflection image.
As a result, the range which can be observed during alignment and during measurement has been limited to only a part of the cornea and it has been very difficult to grasp what area of the entire cornea is actually being measured
There has been a certain type of keratometer in which the optical path can be changed over to enable the fore eye portion to be observed, but in such keratometer, measurement must be effected with the optical path returned to its original position and thus, the aforementioned disadvantage has been unavoidable during measurement.